Abstract: In order to satisfy the requirement of the air traffic control and the battle-filed command system, a three-dimensional (3D) tracking algorithm in distributed two-dimensional (2D) radar network is proposed. Firstly, this paper starts from the generalized measurement equation at the fusion center under the centralized framework, and derives the update equation. Then, the target 3D state is estimated by substituting the measurement term in the update equation with each local radar tracking information. Judging from the derivation, the proposed algorithm is obtained by centralized fusion method with measurement expansion and matrix transformation directly, and it is a suboptimal algorithm due to the approximation of the tracking model of single radar. Finally, Monte Carlo simulations show that the proposed method has fast convergence speed and achieves good tracking accuracy, thus it can meet the need of the real application.